City Takes Over Waimanalo Sewage Plant From State
The facility, located at 41-1060 Kalanianaole Highway in Waimanalo, was built in 1969 and placed in service in 1972 by the state’s Department of Land and Natural Resources (DLNR). The City’s Department of Environmental Services operated the plant under a 1972 agreement with DLNR.
The plant services a portion of the Waimanalo District. It has a capacity of treating 1.1 million gallons of wastewater daily and currently handles a flow of 550,000 gallons. The plant uses secondary treatment plant and sand filtration that discharges the effluent in 10 underground injection wells at 200-foot depths. Sludge generated at the facility is taken to the Kailua Regional WWTP for final processing before landfilled. The plant is producing very high quality effluent based on levels of biological oxygen demand (dissolved organic matter) and turbidity (undissolved solids), and ranks as one of the top three of 12 plants on the island.
DLNR spent approximately $28 million to upgrade the facility to meet City requirements and 2020 design flows and loads. Those upgrades were completed in July 2008.
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